Gear pump or motor



Dec; 20, 1966 R. o. GORDON GEAR PUMP 0R MOTOR 6 Sheets-Sheet 1 Filed April 26, 1965 FIG. I

INVENTOR RlCHARD 0. GORDON ATTORNEY Dec. 20, 1966 R. o. GORDON GEAR PUMP 0R MOTOR 6 Sheets-Sheet 2 Filed April 26, 1965 INVENTOR RICHARD O. GORDON ATTORNEY Dec. 20, 1966 R. o. GORDON GEAR PUMP OR MOTOR 6 Sheets-Sheet 5 Filed April 26, 1955 INVENTOR RICHARD O. GORDON ATTOR N EY 6 Sheets-Sheet 4 Filed April 26, 1965 Fla-i4 INVENT RICHARD Q. GOR

ATTORNEY 6 Sheets-Sheet 5 Filed April 26, 1965 INVENTOR I RICHARD O. GORDQN wy/ ATTORNEY Dec. 20,1966 R. o. GORDON GEAR PUMP OR MOTOR 6 Sheets-Sheet 6 Filed April 26, 1965 INVENTOR RICHARD O. GORDON t W ATTORNEY United States Patent 3,292,550 GEAR PUMP 0R MOTOR Richard 0. Gordon, Mequon, Wis., assignor to Clar Equipment Company, a corporation of Michigan Filed Apr. 26, 1965, Ser. No. 450,842 16 Claims. (Cl. 103-126) This invention relates to fluid displacement pumps and motors, and more particularly to improvements in pressure loaded gear pumps and motors.

Numerous problems have been encountered in the art of pressure loaded gear pumps and motors, particularly those designed for generating relatively high discharge pressures and which are operable at high mechanical and volumetric efiiciencies, as well as being capable of high performance operation for relatively long periods of time with minimum maintenance, concerning which many and varied solutions have been previously proposed. The nature of the problems encountered heretofore and the prior art are discussed in my Patent No. 3,137,238, granted June 16, 1964.

The present invention is concerned with these same problems, as well as with other problems, as will be discussed hereinafter, and includes relatively radical structural innovations in the art. In addition to providing novel solutions to the so-called pressure gradient and related gear pump problems, all as discussed in my said prior patent, the present invention is directed to the solution of additional prior problems in the art, such as the tendency of prior gear pump and motor bodies to bow or deflect radially outwardly during operation, prior requirements to maintain close tolerances between the mating sections of pump cover and body housing sections, the complex problem of selection of the proper pump pressure responsive area in pressure loaded gear pumps (i.e., the thrust plate area which is normally subjected to pump discharge pressure or some fraction thereof in order to properly seal the side faces of the gears), and the requirement in many prior art pumps of costly permanent mold body portions. My invention provides a structure which is capable of being embodied in an extremely simple and low cost pump or motor design which eliminates the previous necessity of always providing separate pressure sealing thrust plates in pressure loaded gear pumps and motors. In other words, one embodiment of my invention provides the advantages of a pressure loaded type pump or motor without requiring the use of separate thrust plates for sealing the side faces of the gears. This is done by providing a novel pump structure which enables surface walls of the housing sections to be used for the same purpose in operation as have been always heretofore provided by separate thrust plate elements. Also, my invention enables a die cast pump body housing to be used, it greatly simplifies the design of thrust plates in embodiments thereof which utilize separate thrust plates, it minimizes or eliminates radial deflection of the pump body, and it simplifies the problem of thrust plate design, all the foregoing advantages being in addition to the provision of generally novel pump structure directed to the pressure gradient problem.

It is therefore a primary object of the invention to provide a vastly improved construction of pressure loaded gear pumps and motors.

Another object of my invention is to provide telescopical housing sections in a gear pump or motor such that radial deflection of the pump body housing is minimized.

Another significant object of the invention is to provide in pumps and motors of the type contemplated a pressure loading system in which pressure fluid reacts directly upon main housing portions of the pump such that the invention may be implemented either with or without the use of separate pressure loaded thrust plates.

3,292,550 Patented Dec. 20, 1966 "ice Another object is to provide a self-aligning gear pump or motor construction.

A further object is to provide improved pressure gradient control means in pumps and motors of the type contemplated.

A still further object is to provide a basic gear pump or motor design which is extremely flexible and adapted to numerous embodiments.

Other objects, advantages and features of the present invention will become apparent to persons skilled in the art from the following detailed description of exemplary embodiments thereof taken in conjunction with the draw ings wherein:

FIGURE 1 is a longitudinal sectional view of a pressure loaded type, intermeshing gear pump or motor taken along the line 1--1 of FIG. 2 in accordance with one embodiment of the present invention;

FIGURE 2 is a partial sectional end view taken along line 22 of FIG. 1;

FIGURE 3 is a longitudinal sectional view of another embodiment of the invention taken along line 3-3 of FIG. 4;

FIGURE 4 is a partial sectional end view taken along line 44 of FIG. 3;

FIGURE 5 is a longitudinal sectional view of another embodiment of the invention taken along line 55 of FIG. 6; and

FIGURE 6 is a partial sectional end view taken along line 6-6 of FIG. 5.

Referring now in detail to FIGS. 1 and 2, numeral 10 denotes a suitably chambered gear pump in which are rotatably mounted a driven gear 12 and an intermeshing driving gear 14. Driven gear 12 is supported on a shaft 16 journaled on its right side in a roller bearing 18 and on its left side in a roller bearing 20. Bearing 18 is located in a chamber 22 and is maintained in position by a thrust plate 24 located intermediate the bearing and the side face of gear 12 and providing an annular recess 26 in registry with the left end portion of the bearing. Bearing member 20 is similarly mounted in a housing chamber 28 in registry with an annular recess portion 30 of a thrust plate 32 located intermediate said bearing and the other side face of gear 12. Driving gear 14 is mounted for rotation upon a drive shaft 34 journaled on its right side in a roller bearing 36 and intermediate its ends in a roller bearing 38, said roller bearings being mounted in chambers 40 and 42, respectively, in a manner similar to the mounting of bearings 18 and 20. Thrust plates 44 and 46 are mounted intermediate opposite sides of gear 14 and the respective bearings 36 and 38 in a manner similar to the mounting of thrust plates 24 and 32; said pairs of plates 24 and 44, and 32 and 46 mating in sealing relationship along complementary flat surfaces indicated at numerals 48 and 50, respectively.

A pump body housing 52, in which is formed the chambers 22 and 40, and a gear chamber 56, has also formed therein an inlet conduit 54 adapted to be connected with a sump, not shown, for conducting inlet pressure fluid to the inlet portion of the gear chamber 56 in a wellknown manner, which gear chamber is formed within an axially extending, annular cantilevered portion 58 of the pump body housing. Also provided in the body housing 52 is a discharge pressure conduit 60 for conveying pressure fluid from the discharge side of the pump, or, in the event unit 10 is used as a hydraulic motor, conduit 60 is utilized as an inlet pressure conduit and conduit 54 as a discharge pressure conduit.

A pump cover housing 62 forms chambers 28 and 42, and a chamber 64 for housing a drive shaft sealing assembly 66 held in position by a snap ring 68. An outer annular cantilevered portion 70 of the cover housing outer threaded diameter and the inner annular diameter of ring 72. If desired, the retainer ring can be constructed to threadedly engage annular surface 80 of housing 52 and to slidably engage the annular outer end portion of housing section 70, thereby reversing the illustrated connections of the retainer ring to the housing portions.

Chambers 22, 28 and 40, a housing passage 90 and a passage 92 in shaft 16 are adapted to collect and direct leakage fluid along shafts 16 and 34 and through the supporting bearings therefor to inlet conduit 54 by a passage, not shown.

Outer annular housing portion 70 forms with inner annular portion 58 a narrow annular clearance chamber 100 which communicates with pump discharge pressure by way of the passage 102, which is connected to discharge conduit 60, and with inlet pressure by way of a passage 104, which is connected to inlet conduit 54, passages 102 and 104 being formed in the pump body housing portion 58. A pair of outer O-rings 106 and 108 are located in housing portion 70 for sealing chamber 100 from communication with other portions of the pump, except by way of passages 102 and 104. In addition, a pair of axially extending flexible sealing bars 110 and 112 are mounted at predetermined locations in housing portion 70 and extend transversely between O-rings 106 and 108 for dividing chamber 100 in two separate pressure areas, viz, an annular portion 100' (FIG. 2) which receives dis charge pressure fluid by way of passage 102, and an annular portion 100" which receives inlet pressure fluid by way of passage 104. The location of sealing bars 110 and 112 is predetermined so that the sealed annular section 100 corresponds to a number of degrees of rotation of gears 12 and 14 in which the gear pockets are normally subjected to pump inlet pressure, whereas the chamber formed by annular section 100" on the opposite side of sealing bars 110 and 112 extends around the housing portion 58 a number of degrees which corresponds to the number of degrees of rotation of the gears in which the gear pockets are normally subjected to pump discharge pressure, or some proportion thereof substantially in excess of inlet pressure. Thus, during pump operation the outer annular chamber 100 is pressurized so that it counteracts the pressure forces within the gear pockets acting radially outwardly thereof on the inner annular surface 56 of housing portion 58, thereby preventing the tendency of housing portion 58 to bow or deflect radially outwardly away from the periphery of the gear teeth,

thus'preventing or minimizing clearance beyond normal running clearance between the periphery of the gears and the gear chamber defining surface 56. Such bowing or deflection of housing parts in prior pump constructions has not only reduced pump efficiency as a result of discharge pressure fluid tending to cascade back to the inlet through an area which varies with the amount of deflection of the housing, as aforesaid, but also results in internal pump forces which tend to reduce the longevity of the pump bearings.

It should be understood that many design variations are available within the scope of the concept above described involving the use of telescoping housing sections providing a sealed annular chamber 100 which may be divided in two or more sealed partial annular pressure chambers, as will become apparent following the description of the embodiment shown in FIGS. 3 and 4. It will also be understood that the spacing of O-rings 106 and 108, and the resulting length of sealing bars 110 and 112, may be varied as desired to provide radially inwardly directed forces which counteract, as may be required by the design'criteria of any given pump construction, the outwardly directed radial forces resulting from the fluid pressure generated in the gear pockets.

Presently available gear pumps are constructed of two 05 three non-telescopic housing sections, normally bolted together in aligned coplanar relation to provide an outer housing shell, whereas my pump body housing 58 comprises an interior housing shell. Prior art pump constructions therefore generally require a non-porous permanent mold pump body housing. In the present invention a relatively porous die cast body housing can be used which is relatively low in cost; this for the reason that little or no leakage from the gear pockets can flow through a relatively porous die cast housing section 58 since counteracting pressure fluid is present in chamber 100, as well as in annular chamber 76, as will presently appear.

Annular chamber 76 comprises a sector 76' and a sector 76" which are formed on opposite sides of a pair of flexible seal-ing bars '114 and 116 mounted in grooves formed in body housing 58 and extending into and transversely of chamber 76 for sealing chamber portion 76' from portion 76". As shown in FIGS. 1 and 2, sealing bars 114 and 116 lie in the same plane as bars and 112, respectively, although it will be apparent that the location of sealing bars 114 and 116 may be varied in design as desired to provide either a larger or smaller chamber sector 76". The selected location of the sealing bars should preferably be such that the annular sector 76" corresponds to the angle of rotation of the gears from zero degree position toward the outlet through which the gear pockets transport substantially inlet pressure fluid. Chamber sector 76' is vented by a plurality of circumfere-ntially spaced passages 120 to different circumferentially spaced portions of the gears such that the chamber sector 76' during different pump operating conditions may be subjected to varying pressure fluids adjacent the openings of the various passages 120 to the chamber 76' depending upon the gradient of pressure which may be present in the various gear pockets from a minimum of inlet pressure to a maximum of discharge pressure, all in accordance with the various factors affecting gear pump pressures and gradients thereof as discussed in detail in my Patent 3,137,238. If the pressure loading of the thrust plates on the gears is less than is required to properly seal the side faces of the gears, the sealing bars 114 and 116 may be relocated closer to the inlet side of the horizontal axis of the pump, whereas if the pressure loading is greater than is required the bars may be located further around the periphery of the chamber 76 so as to enlarge chamber sector 76' and decrease the area of chamber sector 76". An important advantage of my pump design lies in the flexibility which it provides in connection with the availability of a large range of possible areas of chamber sectors 76' and 76" as compared with the limited selectivity of control areas on prior art thrust plates.

It should also be observed that, if desired, significant variations in design are available within the concept of my invention as shown in FIGS. 1 and 2. For instance, an eccentric area of chamber 76 may be provided merely by offsetting toward the discharge side of the pump the center of the circle of the inner diameter of retaining ring 72 from the center of the circle of the outer diameter thereof so that the compensating pressure responsive area of chamber 76 decreases continuously from a maximum chamber width at the inlet to a minimum chamber width at the outlet. While I have not shown a complete separate embodiment to exemplify the latter constructional variation, it will be readily apparent to persons skilled in the art how the variation is accomplished by utilizing a retaining ring 72 having an inner diameter 78 with a center oflset towards the discharge side of the pump, as shown at numeral 122, and an outer threadeddiameter having a center at numeral 124 (FIG. 2). The

configuration of chamber 76 is formed thereby as shown between the circle of the outer diameter and the broken line circle of the inner diameter, as shown in FIG. 2 at numeral 126. Thus, it will be seen, that the flexibility of design indicated above is further broadened by providing both an eccentric retaining ring 72 to vary as desired the effective area of pressure chamber 76, combined with a selected location of sealing 'bars 114 and 116, as may be required. It will be appreciated that if an eccentric retain-iug ring is used it may be found unnecessary to use a plurality of pressure gradient passages 120, as shown in FIG. 2, except for one or two passageways which communicate chamber sector 76' with pump discharge pressure, as shown at 120', whereby the entire area of chamber sector 76' is subjected to pump discharge pressure regardless of the pressure gradient which may exist in the gear pockets. The compensation of pressure gradient in this instance, at least during normal conditions of pump operation in which a pressure gradient is encountered from the inlet to the outlet, is accomplished by means of the eccentric retaining ring 72 which provides a continuously varying area from the inlet to the discharge of the pump. The theory of pressure gradient compensation in gear pumps by utilizing an eccentric area thrust bushing is described in Patent No. 2,823,615, issued in the name of Haberland.

In operation, the gears are rotated with shafts 16 and 34 in the direction shown by the arrows in FIG. 2 to transport and pressurize fluid entering the pump chambers from inlet conduit 54 to outlet conduit 60. In normal pump operation on oil with little or no air entrained in the oil, pump discharge pressure will be present in the gear pockets adjacent all of passages 120 and 120' to effect a discharge pressure response throughout chamber sector 76', whereas an inlet pressure is communicated to chamber sector 76 by way of passageways 130, so that body housing 58 tends to move axially leftwardly, as seen in FIG. 1, to exert a pressure sealing force through thrust plates 24 and 44, gears 12 and 14 and thrust plates 32 and 46 so that the left hand side of the latter thrust plates seal upon the adjacent surface of cover housing 62 and the side faces of the gears are held in pressure sealing contact with the opposed surfaces of the pairs of thrust plates. It will the noted that an outer annular chamber 132 is formed between the cover housing 62 and the end of the telescoping portion 58 of body housing 52, which construction is preferred in order that the sealing force is always exerted between the thrust plates and gears, and not between the end of housing portion 58 and cover housing 62, as would be the case if housing portion 58 extended leftwardly :beyond the assembled thrust plates and gears. In other words, by shortening slightly the annular housing portion 58, as shown, to provide a chamber 132, manufacturing problems are minimized.

It will now be appreciated that during operation all pressure gradient compensated pump sealing forces are applied externally of the pump body housing in chamber 76 which, as aforesaid, promotes maximum flexibility in the design of pumps which may have widely different operating requirements. Another of the important advantages of the present invention is related to the selfaligning feature inherent in the use of telescoping housing sections pressurized to effect a pulling of the housing sections together, which are thereby always inherently positioned as required to establish the proper relationship of all axially movable parts in the pump.

Referring now to FIGS. 3 and 4, parts similar to those described above in respect of FIGS. 1 and 2 are identified by the same numerals with the addition of the subscript a. The structure of this second embodiment of my invention is similar in all respects to the embodiment of FIGS. 1 and 2, except that I have substituted static pressure gradient compensation in chamber 76a as distinguished from the dynamic pressure gradient compensa- 6 tion in chamber 76 of FIG. 2, and have multiplied the division of fluid pressures active in annular clearance chamber a by providing additional sealing bars in said chamber, all as will become apparent from the following description. It should be understood that dynamic pressure gradient compensation, as related to the embodiment of FIGS. 1 and 2, relates primarily to the fact that the various passages and 120 are in communication with each other in chamber sector 76' so that pressure fluid can flow in chamber 76' under the pressure gradient conditions existing in the pumping chamber during operation, whereby to establish a mean effective fluidpressure in chamber 76' to seal the side faces of the gears by means of the thrust plates as required under differing conditions of operation during which the pressure gradient may vary substantially. The principles of dynamic pressure gradient compensation and preferred means for effecting same are set forth in detail in my Patent 3,137,328. In the present embodiment static pressure gradient compensation is utilized by separating chamber 7611 into a plurality of separate chambers, each of which is subjected to the existing pressure in the gear pockets adjacent the respective chambers formed by the sealing bars 114a, 116a and 132. The sealing bars form a plurality of circumferentially spaced chambers 76a" and 134, each of which chambers is responsive to the pressure existing in the gear pockets adjacent the communicating passages 120a, 120a and a. The theory of pressure gradient compensation in gear pumps by utilization of static pressure response in a plurality of sealed chambers is described in Patent No. 2,809,592, issued in the names of of Miller et al. It will be noted that although the various passages 120a and 120a do not communicate with each other, each chamber 134 is responsive to the pressure existing in an adjacent portion of the pumping chamber so that the sealing force exerted by body housing 52a on the thrust plates and gears varies in direct proportion to the particular pressure gradient conditions existing at the time in the pumping chamber, thereby effecting approximate pressure compensation throughout the various chambers in annular chamber 76:: as may be required under different conditions of operation.

In addition, outer annular clearance chamber 100a is divided in the present embodiment in four symmetrically related chamber sectors by sealing bars 110a, 112a, 136 and 138 so as to vary the pressurein different portions of chamber 100a in accordance with a pump chamber pressure adjacent to each individual chamber sector. Passage 102a communicates discharge pressure to annular chamber sector 140, passageway 104a communicates inlet pressure to chamber sector 142, and passageways 120a, 144 communicate the pump chamber pressure in the gear pockets adjacent thereto to upper and lower chamber sectors 146. Of course, if desired, sealing bars 136 and 138 can be duplicated at the location of division of each of the chambers 134 to effect a yet further refinement in pressure gradient control in annular clearance chamber 100a.

A greatly simplified, less costly, and, in many respects, preferred embodiment of my invention is illustrated in FIGS. 5 and 6, which provides for the first time the basic simplicity and low manufacturing cost of fixed clearance gear pumps in a pressure loaded pump. The over-all configuration of the pump shown in FIGS. 5 and 6 is generally similar to the previous embodiments, except that the provision of a plurality of separate thrust plates and of annular sealing rings and sealing bars of the previous embodiments has been completely eliminated without materially affecting the efficiency and operational characteristics thereof. Similar parts have again been similarly numbered as in FIGS. 1 and 2 with the subscript b. In the present embodiment telescoping outer and inner housing portions 70b and 58b have machined mating annular surfaces providing a piloted sliding fit between the said housing portions so that it is not possible, considering the long axial length of the mating surfaces 150, for body housing 52b to cock relative to cover housing 62]), as would occur under pressure gradient conditions in the operation of the previous embodiments, in view of the annular clearance chambers 100 and 100:: provided therein but for the variable pressure response in the chamber sectors of chambers 76 and 76a which is effected by the various sealing bars located in said chambers in order to compensate for said pressure gradient.-

It will be appreciated that by eliminating the annular clearance chambers 100 and 100a between the telescoping housing portions, many of the major complexities of the prior art involving varied structural implementations to compensate for pressure gradient are eliminated. This is accomplished by using an external pressure chamber 76b acting on the elongated internal telescoping body housing 52b so that the body housing itself functions as a piloted thrust plate on the side faces of gears 12b and 14b irrespective of the existence of or any changes in pressure gradient in the pump chamber. Furthermore, the effective area on which the pressure fluid in chamber 76b acts may be varied, as desired, between wide limits simply by providing, for example, an eccentric annular surface area of retaining ring 72b, as discussed previously in connection with FIGS. 1 and 2.

It is to .be again stressed that the flexibility in design in the use of the invention is maximized because of the varous structural features discussed hereinabove, and this is particularly so in connection with the important matter of establishing an effective area of external thrust chamber 76, 76a or 76b which is not limited, as before, to the area of floating thrust plates having an outer diameter equal to the outer diameter of the gears and upon which the pump chamber pressure acts directly. The prior art is therefore, limited inherently to a compensating thrust plate area configuration which is confined within the outline or periphery of the thrust plate itself, which has always before necessarily had an effective outer diameter equal to the gear diameter.

Passages 120b communicate pump chamber pressure fluid to chamber 76b, the same as in the previous embodiments, and because it is not possible in this design for the body housing 52b to cook at an angle relative to the vertical axis of the gears, it is not necessary to divide chamber 76b in separate pressure compartments, although, if desired, the portion of chamber 76b adjacent the inlet of the pump may be sealed from the remainder of the chamber by sealing bars such as shown at 114 and 116 in FIG. 2. In order to provide, however, for some pressure gradient response in chamber 76b, it is advisable to provide a plurality of passages 12% so that the sealing force is not too large. The right-hand side faces of the gears, as viewed in FIG. 5, may be sealed directly by the adjacent annular surface 152 of body housing 52b, although, if desired, a thin flexible figure-8 sealing or wear plate, such as a steelbacked bronze plate, may be inserted between the side face of the gear and housing surface 152. It will be noted that the embodiment of FIG. 5 does not provide a clearance chamber 132, as in FIG. 1, the annular housing portion 58b preferably having an annular end surface 154 which is slightly to the left of the left-hand side of the gears. Inserted between surface 154, the adjacent side of the gears and housing surface 156 is a figure-8 type flexible sealing plate or wafer 158, which includes a small annular depression or step at 160 so that pressure fluid cannot leak back to inlet through the various vpump leakage passages and chambers. Any fluid leakage from the pumping chamber which may occur will flow along the shafts 16b and 34b through the various bearings, passages and chambers at the ends of the shafts back to pump inlet, the same as in the previous embodiments.

From the foregoing it is believed that those familiar with the art will readily recognize and appreciate the novel concepts fiatures of the present invention. While the invention has been described in relation to only four embodiments, numerous variations, changes, and substitutions of equivalents will present themselves to persons skilled in the art, and may be made without necessarily departing from the scope and principles of the inventions. As use throughout the disclosure and claims, the term pump should be understood to also apply to hydraulic gear type motors. It is not my intention to be limited to any particular form of the invention herein illustrated and described except as may appear in the claims appended.

I claim: 7

1. In a gear pump or motor, a generally cup-shaped pump body housing forming a pump chamber internally thereof, shaft supported intermeshing gears in said cham her, a generally cup-shaped pump cover housing telescoped over the body housing and closing the open end thereof, the base end of said body housing extending through the open end of said cover housing and forming a portion of the outer shell of the pump, and means connecting said cover and body housings for limited relative axial movement during operation of the pump.

2. In a gear pump or motor, a generally cup-shaped pump body housing, shaft supported intermeshing gears in the chamber formed by said housing, a generally cupshaped pump cover housing telescoped over the body housing and closing the open end thereof, and an an nular retaining means secured to one of said housings and overlapping an adjacent base end portion of the body housing, a base end portion of the body housing forming a portion of the outer housing shell of the pump.

3. In a gear pump or motor, a pump body housing having an elongated annular body portion cantilevered from an integral end body portion forming a pump chamber, shaft supported intermeshing gears in said chamber, and a pump cover housing including an elongated annular body portion assembled radially outwardly of and in telescoping sliding relation to said first cantilevered body portion and cantilevered from an integral end body portion, said end body portions forming opposite side outer shell housing portions of the pump.

4. A gear pump or motor as claimed in claim 1 wherein said connecting means forms with said body housing a motive fluid pressure chamber.

5.'A pump or motor as claimed in claim 1 wherein the body housing is piloted in close fitting slidable telescoping relation within said cover housing so that said body and cover housings are assembled in confronting body housing, which is telescoped slidably within the cover housing, forms therewith an elongated annular chamber, and means communicating said chamber with pump generated pressure fluid which reacts radially inwardly of said body housing thereby tending to prevent deflection of said body housing.-

7. A pump or motor as claimed in claim 6 wherein sealing means extends across said annular chamber dividing said chamber in more than one compartment, and passage means connecting said compartments to different portions of the pump chamber.

8. A pump or motor as claimed in claim 1 wherein a pressure chamber is formed between said connecting means and said body housing, sealing means extending across said chamber and dividing same in a plurality of compartments, and passage means connecting said compartments with different portions of the her.

9. A pump or motor as claimed in claim 1 wherein thrust plate means are interposed between said body and cover housings and the side faces of said gears on opposite sides of said gears, and a fluid pressure responsive chamber formed between said connecting means and said pump chambody housing responsive to pressure in the pump chamber for actuating said thrust plates to seal the side faces of the gears.

10. A pump or motor as claimed in claim 1 wherein -a fluid pressure chamber is formed between said connecting means and body housing which communicates with pump chamber pressure, and sealing means interposed between at least one side of the gears and the ad jacent housing surface through which one of the pressure actuated housing portions acts to seal one side face of the gears.

11. A gear pump or motor as claimed in claim 4 wherein passage means connects said motive pressure chamber to said pump chamber, said body housing being responsive to pressure in said motive pressure chamber for effecting sealing of the one side faces of said gears.

12. In a gear pump or motor, a pump body housing forming a pump chamber, shaft supported intermeshing gears in said chamber, a pump cover housing in telescoping relation to the body housing, and means connecting said cover and body housings for relative axial movement and forming with said body housing a fluid pressure chamber, said body and cover housings together with said connecting means forming the outer shell housing of the pump, said fluid pressure chamber communicating with pressure fluid in the pump chamber, said body and cover housings being responsive to the fluid pressure in said pressure chamber and tending to be pulled together thereby in axially opposite directions to effect sealing of the opposite side tfaces of the gears.

13. In a gear pump or motor, a body housing having a generally U-shaped cross-sectional configuration, shaft supported intermeshing gears in said body housing, a pump cover housing surrounding said body housing in slidable telescoping relation therewith and also having a generally U-shaped cross-sectional configuration, and means operatively connected to the open end of said cover housing and the base end of said body housing, at least a portion of the base end of the body housing extending into the open end of the cover housing and forming a portion of the outer shell housing of the pump in combination with said means connecting the cover and body housings.

14. In a gear pump or motor, a pump body housing forming a portion of the outer shell housing of the pump, shaft supported intermeshing gears in said body housing, a pump cover housing in telescoping relation to the body housing and forming a portion of the outer shell housing of the .pump, means connecting said cover and body housings for axial movement of the housings in opposite directions during pump operation and forming with said body housing a chamber in communication with a pump generated pressure to which said body and cover housings respond for sealing the side faces of the gears, the effective area and configuration of said pressure chamber being selectable independently of the area and configuration of the side faces of said gears and being remote from said side faces.

15. In a gear pump or motor, a pump body housing forming a pump chamber, shaft supported intermeshing 6 gears in said chamber, a pump cover housing open at one end and in telescopic relation to the body housing and forming therewith an annular chamber, means communicating said chamber with pump generated pressure fluid which reacts radially inwardly of said body housing tending to prevent the deflection of said body housing, sealing means extending across said annular chamber dividing said chamber in more than one compartment, passage means connecting said compartments to different portions of the pump chamber, and means connecting said cover and body housings for limited relative axial movement.

16. In a gear pump or motor, a generally cup-shaped pump body housing forming a pump chamber internally thereof, shaft supported intermeshing gears in said chamber, a. generally cup-shaped pump cover housing telescoped over the body housing and closing the open end thereof, said body and cover housings being mounted in confronting [relation so that the base end of one of said housings is located adjacent the open end of the other of said housing and at least a portion of the base end of said body housing extending through the open end of said cover housing, an annular connecting means operatively connected to the open end portion of said cover housing and the base end portion of said body housing, said connecting means forming with a portion of the base end of said body housing a fluid pressure chamber, said fluid pressure chamber communicating with fluid pressure in said pump chamber, said body and cover housings being responsive to the fluid pressure in said pressure chamber such that an increase in said fluid pressure tends to pull together said cover and body housings in axially opposite directions to effect sealing of the opposite side faces of the gears, said cover and body housings and connecting means together forming the outer shell housing of the pump.

References Cited by the Examiner UNITED STATES PATENTS 1,595,982 8/ 1926 Appel 103126 1,880,108 9/ 1932 Ross 103126 2,470,355 5/ 1949 La-uck 103126 2,649,740 8/ 1953 Murray et a1. 103126 2,837,031 6/ 1958 llune 103 l26 3,034,448 5/ 1962 Brundage 103-126 3,073,251 1/1963- Weigert 103126 3,137,239 6/ 1964 Da'hl 103126 FOREIGN PATENTS 450,436 10/ 1927 Germany.

46 0,624 6/ 19-28 Germany.

572,631 3/ 1933 Germany.

References Cited by the Applicant UNITED STATES PATENTS 2,809,592 10/1957 Miller et al. 2,823,615 2/ 1958 Haberland. 3,137,238 6/ 1964 Gordon.

WILBUR J. GOODLIN, Examiner. 

1. IN A GEAR PUMP OR MOTOR, A GENERALLY CUP-SHAPED PUMP BODY HOUSING FORMING A PUMP CHAMBER INTERNALLY THEREOF, A SHAFT SUPPORTED INTERMESHING GEARS IN SAID CHAMBER, A GENERALLY CUP-SHAPED PUMP COVER HOUSING TELESCOPED OVER THE BODY HOUSING AND CLOSING THE OPEN END THEREOF, THE BASE END OF SAID BODY HOUSING EXTENDING THROUGH THE OPEN END OF SAID COVER HOUSING AND FORMING A PORTION OF THE OUTER SHELL OF THE PUMP, AND MEANS CONNECTING SAID COVER AND BODY HOUSINGS FOR LIMITED RELATIVE AXIAL MOVEMENT DURING OPERATION OF THE PUMP. 